Yang, SI; Kim, BJ; Lee, SY; Kim, HB; Lee, CM; Yu, J; Kang, MJ; Yu, HS; Lee, E; Jung, YH; Kim, HY; Seo, JH; Kwon, JW; Song, DJ; Jang, G; Kim, WK; Shim, JY; Lee, SY; Yang, HJ; Suh, DI; Hong, SA; Choi, KY; Shin, YH; Ahn, K; Kim, KW; Kim, EJ; Hong, SJ; COCOA Study Group